Fixture for holding thread-cutting tools while grinding the cutting edges



H. GIBARTH.

FIXTURE FOR HOLDING THREAD CUTTING TOOLS WHILE GRINDING THE CUI'TING EDGES.

APPLICATION FILED 05c. a0. 1918.

1,368,472; Patented Feb. 15,1921.

J7: zbnior l UNITED s'rA'rns PATENT OFFICE.

HARRYGz EARTH, OF CLEVELAND, OHIO.

FIXTURE FOR HOLDING THREAD-CUTTING TOOLS W'HILE GRINDING THE CUTTING EDGES.

To all 20 700m it may concem Be it known that I HARRY G. EARTH, a citizen of the United ctates, and resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Fixtures for Holding Thread-Cutting Tools While Grinding the Cutting Edges, of which I hereby declare the following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

The objects of the invention are to provide an efficient and practical fixture or means for holding thread cutting tools while grinding the cutting edges thereon.

By means of this device, the cutting edges :an be accurately ground and the desired angle for the thread can be produced with perfect accuracy, and without danger of making any mistake.

The invention comprises a. block in which the tool is clamped, and which is provided with several faces upon which it can rest upon an accurately planed movable guide plate underneath a grinding disk, and the several faces are angularly disposed so that when the block is lying upon a selected face, and moved under the grinding disk, the aforesaid disk will cut away the point of the tool at the angle desired. The block is provided with four such faces to enable the tool to be presented to the grinder in such a manner as to cut away the point in four different planes.

' The invention is illustrated in the accompanying drawings hereinafter more fully described, and definitely formulated in the claims.

In the accompanying drawings Figure l is a plan of the device;

Fig. 2 is a side elevation of the device showing the tool secured for grinding the flat upper face thereon;

Fig. 3 is a. front elevation;

Fig. i is a rear elevation;

Fig. 5 is an elevation showing the device laid upon one inclined face and presenting the tool to the grinder in such a manner as to cut one of the inclined faces of the point;

Fig. 6 is a similar view showing the device arranged for cutting the opposite inclined face of the point at an equal angle.

Fig. 7 is a side elevation, showing the device laid upon its back, so as to present the Specification of Letters Patent.

Patented Feb. 15, 1921.

Application. filed December 30, 1918. Serial No. 268,927.

flatten the point to aroduce the fiat bottom of the groove of a l S. standard thread.

In these views A is a metal block provided with fiat parallel horizontal upper and lower faces, B and C respectively, a vertical front face D, upwardly and rearwardly inclined side faces E, and F, and an upwardly inclined rear or back face, G.

The tool H is carried in a slot 1, parallel with the longitudinal axis of the block and in the upper face, and secured therein by means of a clamping member J. This member reversible and is provided with a V-sh aped jaw J on one side for securing a. cylindrical tool bar and with a rectangular jaw, J on the other sidefor securing a square tool bar. When the device is laid upon the horizontal bottom face and moved underneath a grinding disk K (shown in dotted lines), a horizontal face Lwill be cut on the upper edge of the end of the tool as shown in Fig. 2.

lVhen the device is laid upon one of the inclined sides as shown in. Fig. 5 and is moved underneath the rinding disk K, one of the inclined faces hf of the point of the tool is cut as shown in Fig. 5.

Inl ig. 6, the device is laid upon the other inclined side and moved underneath the grinding disk to cut the other inclined face N of the point. These inclined faces of the point of the tool are not vertical but are inclined downwardly and inwardly so as to give a projection to the upper extremity of the cutting edge for clearance while entering the work. The sides E and F are inclined in two directions, the amount of incline from the vertical being shown as 10, but it is determined by the amount of clearance desired and the amount of incline from the longitudinal axis of the tool is shown as 30 on each side, which is the angle of the standard screw thread ordinarily employed.

lVhen it is desired to flatten the extreme cutting edge of the oint to produce the flat bottom of the U. standard thread; the block upon the upwardly inclined surface G, as shown in Fig. 7 is then passed underneath the grinder, which removes the sharp point. When the standard V-shaped thread is desired, it is not necessary to use this part of the block, since the inclined sides of the block will produce the necessary clearance when the block is laid upon them.

Modifications in the angles employed may be made to accommodate unusual. conditions of threads or for cutting tool points employed for other purposes, without departing from the scope of the claim.

Openings T, T, are provided in all the bearing faces for attaching the block to a bed, movable or otherwise, or it may be secured upon a magnetic bed.

Having described the invention what I claim as new and desire to secure by Letters Patent is: V

A tool holding means for the purpose described comprising a block, having a horizontal lower surface, and a vertical front face, and provided with opposite sides inclined rearwardly from said front face at equal angles, and alsoinclined from said lower surface at equal angles, and provided with a rear face inclined upwardly from said bottom face at an angle, and tool holding means adjacent the upper surface of said block. 7

In testimony whereof I hereunto set hand this 4th day of December, 1918.

HARRY G. EARTH.

In presenceof- R. W. JEREMIAH, NM. M. MONROE. 

